Air distribution system for a food display case



Nov. 28, 1961 w. A. ARZBERGER EM]. 3

AIR DISTRIBUTION SYSTEM FOR A FOOD DISPLAY CASE Filed May 19, 1958 2 Sheets-Sheet 1 FIG. I

FIG. 3

INVENTORS WILLlAM A. ARZBERGER RICHARD H. SWART SR. BY ELBRIDGEERAUSCHER ATIORNEY ETAL 3,010,379

2 Shecs-Sheet 2 Nov. 28, 1961 w. A. ARZB ERGER AIR DISTRIBUTION SYSTEM FOR A FOOD DISPLAY CASE Filed May 19, 1958 Fig. 7

INVENTORS WILLIAM A. ARZBERGER RICHARD H. SWART, SR. BY ELBRIDGEERAUSCHER grromvm Fig. 6

United States Patent Ofiice 3,010,379 Patented Nov. 28, 1961 3,010,379 AIR DISTRIBUTION SYSTEM FOR A FOOD DISPLAY CASE William A. Arzberger, North Syracuse, and Richard H. Swart, Sr., and Elbridge F. Rauscher, Syracuse, N.Y., assignors to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed May 19, 1958, Ser. No. 736,063 Claims. (Cl. 9836) This invention relates broadly to air distribution systems. More particularly, this invention relates to air distribution systems forming an air curtain for use in refrigerated food display cases, cabinets, containers or receptacles.

It is conventional practice to utilize horizontally oriented air streams with food display cases found in establishments that merchandise refrigerated and frozen foods. In cases of the type in general use, the food is positioned within a container or receptacle and a horizontal stream of refrigerated air serves to blanket the frozen goods placed within the enclosure. Customers desirous of purchasing the frozen food reach down into the case or well through the horizontal curtain to select the food which is, of course, displayed visible to the observer. Similar cases are commonly used for displaying fresh meat, dairy products, and vegetables.

This type of open refrigerated display case has several disadvantages. They occupy a large area of store space. The display is limited and requires reaching back and down, and product labels are at some distance from view. The customers take food from the top where cooling may be insuflicient, and the food in the bottom is apt to remain there longer than desirable.

In these same establishments or stores, unrefrigerated foods such as canned and packaged items are stored on compact accessible vertically arranged tiered shelves, thereby conserving floor area, and facilitating customer selection.

The desirability of having a refrigerated food display unit wherein a vertical air curtain projects across the open front of a refrigerated cabinet having displayed, on multiple tiered shelves therein, the frozen food, has long been known especially in view of the experience displaying unrefrigerated foods. The function of the vertical air curtain in an open front case or cabinet described is to prevent the ambient air from entering the display cabinet and elevating the temperature of the air therein, and to prevent the relatively cold air in the cabinet from escaping, while permitting easy access to the interior of the cabinet.

Heretofore vertical air curtains have proven very expensive to operate. The reason for this is that the refrigerated air is heavier (more dense) than the ambient air and spills out as rapidlyras it is cooled, resulting in excessive refrigeration requirements and non-acceptable food temperatures, as well as the deposit of moisture on the store floor. Another disadvantage in the use of a vertical air curtain are the losses due to the inductive effect on ambient air disposed in the area adjacent the vertical air curtain, particularly near or at its point of supply. Considering the first loss, this phenomena is similar to that which occurs when one opens the door on a domestic refrigerator and the colder air existing in the refrigerator tends to tumble out on the floor in the area adjacent the bottom of'the' unit.

This invention has for its chief object an air distribution system for use with a refrigerated food display case wherein air is projected across the front opening of a food display case in such a manner that losses resulting from the spillout effect are substantially minimized.

, opening of the compartment.

A further object of the invention is a method of distributing air through a frozen food display case so that losses inherent in the operation of vertical air curtains are substantially reduced.

Another object of this invention involves the provision of an air distribution system for use with a frozen food display case that includes an air curtain utilizing air from an air conditioning plant serving the store or establishment housing the case.

The present invention involves an air distribution system forming a vertical air curtain for a food display case comprising means for discharging, across the open front face of the food case, a stream of properly refrigerated air, means for receiving the cold air after its travel across the front access opening of the food display case, means for delivering the discharge air to its original point of travel across the front opening of the food display case, and means utilizing air which has spilled out during its travel across the front access opening for circulation in an air circuit having a portion forming a barrier stream for the first air stream.

These and other objects and features of the invention will be apparent upon a consideration of the ensuing specification and drawings in which:

FIGURE 1 is an exploded view of an air distribution system suitable for use with a food display casing having a vertical air curtain serving to permit access to the interior of the food display case;

FIGURE 2 is an elevational view in section of the unit illustrated in FIGURE 1 with certain parts of the unit shown diagrammatically;

FIGURE 3 is a view from the front of the unit shown in FIGURES 1 and 2 illustrating a portion of the air curtain;

FIGURE 4 is a view similar to FIGURE 1 showing a modification;

FIGURE 5 is a plan view of the modification of the invention with the upper or topmost cover removed;

FIGURE 6 is a side view of the unit shown in FIG- URE 4 with the side panel removed; and

FIGURE 7 is a partial view of another modification of the invention.

Referring to FIGURES l and 2, it will be noted that a frozen food display case 10 of the kind suitable for use with this invention includes a false bottom 11, a rear wall 12 and a false top wall 13 which, with side walls 14 and 15, form a compartment having a substantially vertical open front. Shelves 30 for the reception of frozen food products are shown connected to the side and rear walls.

In order to maintain the interior of the compartment described at a temperature suflicient to ensure the frozen condition of the products within the cabinet, as well as to permit unobstructed access to the interior, a vertical air curtain is provided. As shown, the vertical air curtain is part of an air distribution system including a priinary air circuit which includes a first or lower plenum 16 formed by the false bottom 11 of the compartment and a horizontally disposedouter bottom wall 17. Cooperating with one end of the plenum 16 is a duct 18 formed by the outer wall 19 in conjunction with rear compartment Wall 12. The duct 18 connects the lower plenum 16 with an upper plenum 20. The upper plenum chamber is formed in part by the top wall 13 of the enclosure and outer wall 21. The upper plenum 20 is provided with an outlet portion 22 overhanging the front Air flowing within the upper plenum is discharged therefrom through a grille located in the overhanging portion 22 of the plenum 20. Preferably the grille is formed of a relatively honeycomb-like member 23. Located in substantial alignment with theoverhanging portion 22 of plenum 20 is an extending portion 24 of plenum 16. Air discharged from the portion 22 is received by the extending portion 24 of plenum 16. Fan members 31 are located within the circuit defined by the two plenums, duct 18 and the air curtain to move air in the manner described. The extending portion 24 of plenum 16 is likewise provided with a member similar to member 23 disposed in the overhanging portion 22 of the plenum 20.

In order to regulate the temperature of the air flowing in the circuit described, evaporator 40 of a conventional refrigeration system including compressor 41, condenser 42 and expansion member 43, is provided in the air .circuit. Thus, air flowing in the circuit described will be chilled during its passage over the evaporator 40. Portions of the refrigerated air peel inwardly oflE the curtain stream and chill the products on the compartment shelves.

As stated above, however, a part of the air flowing in the lower portion of the air curtain tends to spill outwardly of the extending portion 24. In order to minimize this loss and thus provide a more eflicient air curtain, it is proposed that a second air circuit be provided. The function of the second air circuit is to provide a separate air stream which will be located contiguous the first air stream described to form a novel air curtain. The secondary air stream thus tends to minimize the thermal gradient due to the presence of the ambient air adjacent the air curtain. Inasmuch as the source of relatively cold 'air is available by virtue of the spillout effect described above, it is proposed that the second air circuit have a portion 45, in the form of a duct, adjacent extending portion 24, to receive the spillout air. Fans 46 are then provided to supply the spilled air through vertical riser ducts 47 to an overhead-supply duct 48 located adjacent to and contiguous to the overhanging portion 22' of plenum 20. The ducts 48 and 45 are likewise provided with a grille element of the type utilized with the portion 22. Thus, in effect, there are two sideby-side'air streams arranged to effectively form a barrier for the entrance of the relatively warm ambient air into the interior of the food display case.

Another form of air distribution system of the kind under consideration involves the construction shown in FIGURE 4. Here, the food display unit is substantially as shown in FIGURE 1, with the exception that the primary air circuit does not have a portion in contact with the rear wall of the unit. Instead, the air received in the lower plenum 49 is directed by fans 56 to ducts 50 and 51 formed by wall members 52 and 53 spaced from sides 14 and 15 and thus transmitted up the sides of the unit to the'top discharge plenum 55. With this arrangement replenishment of the food products supported on the shelves 30 may be accomplished through rear door 60 in rear wall. A barrier or protective stream of air may be introduced across the front of the unit in the manner proposed in FIGURE 1.

In the embodiment illustrated in FIGURE 7, an additional air stream is provided to either of the forms of the invention as shown in FIGURES 1 and 4. Under these circumstances, it is contemplated that the food display case be utilized in an establishment having an air conditioning system, preferably of the overhead ducttype wherein air is cooled at a central station and supplied to the establishment through a series of overhead ducts having spaced louvered openings. It is proposed that a portion 70 of the overhead duct system be utilized to provide in effect a third air stream which will form with the first two air streams a substantially strong barrier.

It will thus be obvious that we have provided an 'air distribution system which, in turn, provides an effective laminar air curtain covering an exposed front opening to a food display case havingfroz en products arranged therein. 7 i I While we have described a preferred embodiment of our invention, it will be understood that the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. An air distribution system for a refrigerated enclosure having a top wall, a bottom wall, opposed side walls and a rear wall, access to the interior of which is afforded through an air curtain formed by the air distribution system, flowing across the open front of the enclosure, comprising means forming a first circuit for the flow of relatively low temperature air across the front of the enclosure, said means including a first plenum having an opening for discharging the air across the front of the enclosure, a second plenum having an opening for receiving air discharged across the front of the enclosure and ductwork forming a confined passageway providing a path within said first circuit for delivering the air from the second plenum to the first plenum; means for circulating air through said first circuit; means forming a second circuit for the fiow of air at a temperature substantially the same as the temperature of air flowing in said first circuit, said second circuit having a portion extending across the front of the refrigerated enclosure adjacent the portion of the first circuit extending across the front of the enclosure to form a laminar air curtain of low temperature air, and means for circulating in said second circuit the dense air tending to spill out of said first circuit.

2. The invention set forth in claim 1 wherein air flow in said second circuit is in the same direction as air flow in the first circuit.

3. In combination with an enclosure having bottom, rear and side walls, air distribution means for providing an air curtain across the open front of the enclosure, said means including an air supply plenum for discharging a first stream of air across said opening, an air collecting plenum substantially directly below said air supply plenum, duct means connecting said plenums, means for continuously circulating air from said air collecting plenum to said air supply plenum, means for cooling said circulating air and means for projecting a second stream of air substantially parallel to said first stream across the front of said enclosure, said last means including a receptacle having an opening for collecting air spilling' from said first stream and means for circulating the spilled or reclaimed air through a circuit which includes said second stream.

4. The invention set forth in claim 3 wherein said circulating means for circulating air between said air collecting plenum and said air supply plenum includes a fan and duct work forming a substantially closed passageway for air discharged into said second stream.

5. The method of forming an air curtain for a refrigerated enclosure having a single access opening, which consists in the steps of directing refrigerated air through a first circuit, a portion of which includes a path across said opening, collecting air spilling from said path, and circulating said collected air through a second circuit, a portion of which includes a path, contiguous to said first path across said openings so as to form an air curtain consisting of two separate air streams.

References Cited in the file of this patent UNITED STATES PATENTS 

